Association between Medication Adherence and Duration of Outpatient Treatment in Patients with Schizophrenia

Medication adherence is important in the treatment of schizophrenia, and critical periods during treatment may be associated with relapse. However, the relationship between adherence and duration of outpatient treatment (DOT) remains unclear. The authors aimed to clarify the relationship between adherence and DOT at a psychiatric hospital in Japan. For outpatients with schizophrenia who regularly visit Shin-Abuyama hospital, the authors conducted a single questionnaire survey (five questions covering gender, age, DOT, medication shortages, and residual medication) over one month period. Participants were divided into two groups whether DOT were from more than one year to within five years or not. Mantel-Haenszel analysis and logistic regression analysis were performed on the data regarding the medication adherence. Effective answers were received for 328 patients. The residual medication rate was significantly higher among those receiving outpatient treatment from more than one year to within five years than five years than those receiving outpatient treatment for more than five years or less than one year (p=0.016). This survey suggests that there are critical periods during which patients are most prone to poor adherence. Because poor adherence increases the risk of relapse, specific measures must be taken to improve adherence during these periods.